Dynamo electric machine



(No Model.) 2 Sheets-Sheet 1.

J. WENSTRUM.

DYNAMO ELECTRIC MACHINE.

No. 426,576. Patent'edApr. 29, 1890.

u 71/ 71/ 5 I I IN VE/VTUH JH/CLS wenslz 0771 (No Model.) 2 Sheets-Sheet2.

J. WENSTROM. DYNAMO ELECTRIC MACHINE. No.. 426,576. Patented Apr. 29,1890.

INVENTOH Jams wenstrowz/ magnet-poles, and Fig. 5 on a plane f f UNITEDSTATES PATENT OFFICE.

JONAS \VENSTROM, OF OREBRO, SIVEDEN.

DYNAMO-ELECTRIC MACHINE.

SPECIFICATION forming part of Letters Patent No. 426,576, dated April29, 1890.

Application filed August 3]., 1889. Serial No. 322,556. (No model.)

To all whom it may concern:

Be it known that I, JONAS \VENsTRoM, a subject of the King of Sweden,residing in Orebro, in the Kingdom of Sweden, have invented certain newand useful Improvements in Dynamo-Electric Machines, of which thefollowing is a specification.

This my invention relates especially to improvements in dynamo-electricmachineshaving iron-clad field-magnets.

The invention relates to the field-magnets; and it consists inprovisions by which the path of the magnetic lines of force is madeshort and of ample size without sacrificing the space available for theconductors.

Referring to the drawings, Figures 1 to 5 relate to a dynamo with fourpoles, and Figs. 6 and 7 to a two-polar dynamo, in the latter case onlythose sections being shown in which the deviations from the four-polartype will appear. Fig. 1 is a longitudinal section on a plane a athrough the axis of the field-magnet and vertical to the armature-shaft.Fig. 2 is a longitudinal section on a plane 1 1 through the axis of thefield-magnet and the armature-shaft. Figs. 3, 4, and 5 arecrosssections, Fig. 3 on a plane (I d close to the back yoke. Fig. at ona plane 6 6 close to the through the armature-shaft. Figs. 6 and 7 aresections similar to Figs. 1 and 5, respectively, but referring to twopolar dymanos, as said before. The armature is here left out.

In the field-magnets the inner cores m are cylindrical and they havepole-pieces p 011 the end pointing toward each other. Their other endsare cast in one piece with the back yokes g, which on their other rimare provided with broad flanges 7L to insure a tight and large contactat the joint with the surrounding easing r. The magnetizingcoils s andthe inside surface of the casing 0' also are cylindrical. Accordinglyall these parts, which must be fitted together exactly, may be adjustedin the lathe, the simplest and most exact method known. Besides, thewinding of the coils thus is made very easy and uniform when ofcylindrical form.

In the casing the cylindrical form is not retained in the outsidesurface, because it is not so convenient as this form here specified forthe conveying of the magnetic lines through the casing. As the armaturein, with the shaft 6 e and commutator 1', must beinserted through thiscasing, corresponding large openings must be made through it, cuttingaway a considerable part of the conduits for the magnetic lines throughthecas ing and forcing them through the remaining parts. This lengthensthe track for most of the lines and increases the magnetic resist ancein proportion.

The shortest track through the iron, evidently, is as close as possibleto the plane a a, referred to above, and to get most of the lines tofollow this track the iron must be considerably increased in thicknessin that place, but thinned in the vicinity of the plane 1 y, when nomore lines will be conveyed than those resulting from the magnetizationmade in this very place directly by the magnetizing-coils inside; butthe confinement of the magnetic lines to two comparatively narrow partsof the circumference cannot be done at once, as the lines, which areradiating in all directions through the back yoke, will only graduallybe gathered together in the confined space referred to. The thickness ofthe iron must therefore only gradually increase in the vicinity of theplane a a and decrease at the plane I) Z). To fulfill this purpose myinvention consists in making the outer surface 'of oval shape instead ofcylindrical, the ellipses formed by transverse sections, as shown inFigs. 3 and 4, being more oval-via, the departure from the cylinderbeing more conspieuousclose to the poles, Fig. 4, than in the vicinityof the back yoke, Fig. in the yokes and joints the increasing difference in the thickness of the iron at the planes referred to is apparent.Thus the rim will be heavier and the flange broader in places where themeeting casing is thicker, as before explained.

These improvements may be applied as well in field-magnets with fourpoles as in those with two, because the introduction of the two poles atthe middle of the exterior easing makes no difference in the generaldistribution of the magnetic lines in the iron.

The shaft of the dynamo usually is horizontal; but the axis of the fieldmagnets may be Already arranged either horizontally or vertically, Figs.(3 and 7, without interfering with the application of this invention. Ineither case the enveloping casing may be cast in one piece with the footplate or base, as shown in the drawings, and the interior cylinders arefree from it in order to facilitate the winding of the coils on them,these wound cores being afterward put in and bolted together with thecasing. 'When convenient, and this is especially the case in two-polarmagnets, this part of my invention may also be applied withoutusingjoints at h, the exterior core, the back yoke, and the casing being castin one piece. To these field-magnets armatures of any convenient typemay be applied.

Having thus described my invention, I clai1n- 1. The combination, withinterior cylindrical iron cores situated on both sides of the armatureand cast in one piece with polepieces on the ends facing the armatureand with back yokes on the other end and surrounded by cylindricalmagnetizing-coils, of an outer enveloping casing, the interior surfaceof said casing being cylindrical, but the exterior of an oval shape, ofsuch arrangement that the thickest parts of the casing will be situatedat a plane laid through the axis of the field-magnets and perpendicularto the ar1na-' ture-shaft.

2. The combination, with interior cylindrical iron cores situated onboth sides of the armature and cast in one piece with polepieces on theends facing the armature and with. back yokes on the other end andsurrounded by cylindrical magnetizing-coils,of an outer envelopingcasing, the interior surface of said casing being cylindrical, but theexterior of an oval shape, of such arrangement that the thickest partsof the casing will be situated at a plane laid through the axis of thefield-magnets and vertical to the armatureshaft, the difference inthickness of the easin g being more conspicuous in the middle than atthe ends, the transformation of the iron mass being gradually developed,commencing in the back yoke and ending in the middle of the casing.

3. The combination, with interior cylindrical iron cores situated onboth sides of the armature and cast in one piece with polepieces on theends facing the armature and with back yokes on the other end andsurrounded by cylindrical magnetizing-coils, of an outer envelopingcasing, the interior surface of said casing being cylindrical, but theexterior of an oval shape, of such arrangement that the thickest partsof the casing will be situated at a plane laid through the axis of thefield-magnets and vertical to the armature-shaft, said casing beingprovided with poles in the middle, facing the armature.

at. The combination, with interior cylindrical iron cores situated onboth sides of the armature and cast in one piece with polepieces on theends facing the armature and with back yokes on the other end andsurrounded by cylindrical niagnetizing-coils, of an outer envelopingcasing, the interior surface of said casing being cylindrical, but theexterior of an oval shape, of such arrangement that the thickest partsof the casing will be situated at a plane laid through the axis of thefield-magnets and perpendicular to the ar1nature-shaft, saidfield-magnets being arranged with their axis horizontal or vertical, thecasing in both cases being cast in one piece with the foot-plate.

In witness whereof I have hereunto signed my name in the presence of twosubscribing witnesses.

JONAS \VENSTROM. lVitncsses:

N ERE A. ELFWING, HUGO GINTTLER.

